The employment of optical fibers in telecommunications applications requires the ability to switch an optical between optical sources and receptors, such as optical fibers, economically and with a minimum of signal loss. Heretofore, switching between optical sources and receptors has been accomplished using complex optomechanical arrangements.
In U.S. Pat. No. 4,033,669 to Hanson, issued July 5, 1977, switching is achieved by the displacement of one fiber end face relative to a bundle of stationary fiber end faces. This technique is inferior to the present proposal in that a complex assembly of parts is required to meet the precise lateral arrangement between the coupled fiber end faces.
The use of a stationary, concave, spherical reflective surface to couple light from an input fiber to a plurality of output fibers is disclosed in U.S. Pat. No. 3,883,223 to Hudson, issued May 13, 1975. Unlike the present invention, however, there is no ability to switch the optical signal to a preselected fiber.
Most recently, a copending application to Tomlinson-Wagner, filed concurrently and assigned to the same assignee, now U.S. Pat. No. 4,208,094, June 17, 1980, discloses a rotating planar mirror in combination with a one-quarter period rod lens to provide switching. This dependency on a lens, or refractive element, yields a switch in which the output signal varies with changes in the index of refraction and wavelength. Therefore, control of these parameters must be maintained to assure low-loss interconnection.